Boiler control system



April 17, 1934. A DOBLE f 1,955,274

BOILER CONTROL SJYSTEM Fixed may 5, wao 4 Smets-sheetl 1 A TTQRNEYS.

April 17, 1934. A. DOBLE 1,955,274

BOILER CONTROL SYSTEM Filed May 5, 1930 4 sheets-sheet 2 IN VEN TOR.

April 17, 1934. A. DOBLE 1,955,274

' 4BOILIEIR CONTROL SYSTEM Filed May 5, 195o 4 sheets-sheet 3 IN V ENTOR.

A TTORNEYS.

April 17, 1934. l A DOBLE 1,955,274

BOILER coNTRoL SYSTEM Filed May 5, 1930 4 sheets-sheet 4 FMEA- IN VENTOR.

ATTORNEYS.

Patented Ape-17,1934

" "umTEo'sTATE-s PATENT o1-FICE Application May 5, 1930, serial No.449,786 16 claims. (ci. 122-448) This invention relates to a system forcontrol of a fluid heater such as a boiler and particularly to a heaterof the series tube type. The fluid .heater can be employed in a powerplant for a mobile unit as an automobile or for stationary uses/I haveemployed the control system successfully witha boiler, operatin g on vauidas water,- in an automobile and .shall preferably describe'it in thisconnection. j

It is a de sideratum that the boiler be able to deliver steam havingcertain desired characteristics under substantially any load'conditions. With previous boilers ,this has not been possible totherextent desired, the boilerbeing incapable, 1 5 under rapidfluctuations in load, or supplying large quantities of steam of thedesired characteristics under all conditions so that the maximum effortcould be secured from the device utilizing the steam.

In a co-pending application of Warren Doble, filed April 18, 1930,Serialy No. 445,301, entitled Steam power plant, it 'has been proposedto provide a boiler 'structure in which the' quantity of heat releasedto the boiler may be augmented due to lack of heat.

It is accordingly, now possib1eto-`supp1y remtively great quantities ofheat to the boiler'so that the thermal characteristics of steamgenerated in the boiler are maintained at the values de-' V sired. Inaccordance with the present invention, certain advantageous features ofthe aforementioned invention of Warren Doble are utilized to` vpowerplant by controlling thequantity of water` in the proper relationship tothe quantity of heat supplied so that the boiler steams at a relativelyhigh rate. i y

v In accordance with the present invention the operation of the meansfor releasing heat to the vboiler is so regulated that the boilerfurnishes steam of the desired characteristics substantially' inaccordance with'the demand for steamupon I preferably coordinate theheat release means and the Water supply means so that the water isA'proportionedto the heat released to the boiler.

While it is in general the broad object of the so that any incapacity ofthe boilerto provide steam having the desired characteristics isnot' theboiler. This is' largely due to the fact that- `invention .to provide .aboiler control system for securing the-above advantages it is to bepointed out that the invention possesses other advantageous features andobjects some of. which with theforegoing will be set forth in thefollowing specicationand illustrated in the drawings accompanying andforming part of said specification. In the drawings I have shown formsof boiler control systems embodying my invention.4 It is to beunderstood that I am not to be restricted to these forms since theinvention, as defined by the claims, may be embodied in other forms aswell'.

In lthe drawings, Figure 1 is a schematic showing of the boiler controlsystem of my invention.

Figure 2\is a schematicshowing of a similar system but including adifferent water pumping mechanism.

Figure 3 is a schematic showing similar to Figure -2 but with asimplified water controlling 75 mechanism.

Figure 4 is a schematic showing of a further modified form of boilercontrol system in accordance with my invention.

My invention may be briefly characterized as comprising a boiler whichis supplied with heat Y' by suitable meansand with water from asource ofsupply' in accordance substantially with the demand for steam on theboiler, the quantity of the heat released tothe boiler and the quantityof water supplied being always in substantially predetermined mutualproportions despite variations in their rate of supply. Further, thesys- `tem contemplates the regulation of the tempera- 1l througha'conduit l2 into a venturi 13 at the throat of which thecarburetor 9 isplaced. The '100 'carbureted fuel is ignited by the spark plug 14 as itpasses'into the boiler casing il. The blower ll is driven by an electricmotor 23. I

Steam generated in the boiler passesthrough theoutlet pipe 16 to anengine indicated at 17, the 105 supply of steam being regulated by thethrottle valve 18. Exhaust steam from the engine is preferably utilizedto drive suitable powermeans for `supplementing the electric motorfurnishing'- the 'air-fuel mixture to the boiler, although steam can 110be taken directly fromthe boiler, if-desired, to drive the power means.To accomplish the supplementing lof the blower by the turbine, conduit19 conducts exhaust steam yfrom the engine to a turbine 2l mounted upona shaft 22 upon which are mounted the blower l1 and electric motor 23.

Operation of the power plant is controlled by an electrical circuitwhich includes a generator 25 operated by the engine 17 to furnishcurrent to a battery 26. The electrical circuit' is traced through thebattery 26, one side of which is grounded, a master switch 27, movablecontact 28 associated with an adjustable xed contact 29, a movablecontact arm 31 associated with an adjustable fixed contact 32, solenoidvalve mechaf nism .33 which controls admission of exhaust steam to theturbine, electric motor 23, and mechanically actuated interrupter 36Aand coils 37 which furnish the high tension current for the spark plug.The movable* contact 28 is operable by a pressure responsive device 38to open or close the circuit in accordance with boiler pressure whilethe movable contact arm 31 is operable by a 1 l temperature responsivedevice 39 such as a ther- ,25.

'high tension current to the spark plug 14 to ignite the fuel-airmixture which provides a fire in the boiler casing.

When either the temperature or the pressure have reached thepredetermined value,.the temperature responsive ineans or the pressureresponsive means opens the circuit to deenergize the solenoid mechanism33 so that steam is by passed about the turbine 21, to deenergiretheelectric motor 23, and to deenergize the'interrupterelement. and coils37 so that no fire is supplied to the boiler. I

It is to .be noted particularly that with the turbine `21 supplementingthe motor to drive the blower, the fire in the firebox variessubstantially lwith the load on the engine and, further, with the demandon the boiler forsteam.. In accordance with the present invention theproper relationship is maintained between the variable quantity of reand the variable quantity ofwater sothat Ea maximum steaming rate ispossible at al1 times.

In that form of the invention shown in Figure 1,

water is supplied by a pump 51 drawing from tank 52. I prefer thatv thepump 51 be actuated by steam from the outlet conduit 16, thel connectionbeing through a conduit 53 and the passage of steam to the pump Abeingcontrolled by a solenoid throttle and valvev mechanism 54. Also, Iprefer, in accordance with my invention, that the admission of water tothe boiler be. controlled in accordance with such a boiler condition asthe proportion of heat availablewhich is extracted by the water.

lA manner of accomplishing this successfully has been indicateddiagrammatically in Figure '1 -Iwherei'n temperature responsive means 66such as rod 67 of non-expanding material is inserted in an expandingtube 68. The tube is positioned in the boiler so that it is affected bythe fuel gases or products of combustion and is proximate the boilertube 7 to be affected thereby. The temperature of the thermostat 66 onone hand is dependent upon the temperature and velocity of thesurrounding fuel gases which, inturnrare dependent upon the temperatureof the prcidmate boiler tube 7. The thermostat 66 therefore assumes atemperature which is intermediate that of the boiler tube and that whichthe fuel gases would assume were the tube omitted, and which may be saidto be a function of the proportion of heat extracted by the water fromthe heat available. An exact, mathematical expression of this functionis unknown to me, but is immaterial in practice, as will subsequently beexplained.

Joined to the thermostat rod'67 is a rocker arm 69 which carries acontact 71. When the temperature of the thermostat 66 is relativelyhigh, the rod 67 is in such a position that the contact 71 is inabutment. with fixed contact 72 to close a circuit- 73. This circuit istraced through the contacts 71 and 72 through contacts 77 and 78 whichcontrol energization of the solenoid throttle and valve mechanism 54, tosolenoid valve mechanism 74 which controls a bypass 76 from the pump.

In operation, when the temperature of the thermostat 66 is low, theadjustable contact 71 is away from the fixed contact 72 and the solenoidthrottle and valve mechanism 54 is deenergized to cut oil steam to thefsteam pump. The solenoid valve mechanism 74 is also deenergized topermit water to be bypassed from outlet 79 of the pump through a conduit80 back to the tank 52.

.When the temperature of the thermostat 66 increases, the rod 67 ismoved to bring the contactsY 71 and 72 into abutment with the resultthat the bypass valve is closedso vthat water can pass from the pumpinto conduit 81. From this conduit it passes to a. metering device 82having a passageway 83 therein. Communication of the passageway withinlet 84 to the boiler is controlled by means of a valverod 85 operatedby the rocker arm 69 and having a tapered end projecting into thepassageway 83. By shaping the tapered end properly, Athe unobstructedarea of 'passageway 83 can be fixed at any desired amount to pass apredetermined amount of Wwater for any position, i. e. temperature, ofthermostat 66. In practice the contour of the taper is determinedexperimentally for the particular system. It is generally parabolic. Themajor consideration that more water is passedto the boiler tube whenthermostat 66 is relatively hot than is passed to the boiler-'when thethermostat 66 is relatively cold. The device 82 also includes a slidablepis= ton 86 biased bya spring 87 and capable of maintaining a constantpressure drop across the valve 85. To accomplish this it moves up anddown in the metering device to accommodate respectively for lan excessor deficiency in the supply of water from the pump. 'I'he piston 86 hasa rod.88 which extends from the device and carries the contact 77. Withan excess of water and an increase in the pressure drop, the pistonrises to carry the contact 77 away from contact 78 so that admission ofsteam to the pump ceases and bypass 76 opens. 'With va' deficiency inthe supply of water, the piston drops to bring theA contacts 77 los and78 together so that steam passes to the pump and by-pass 76 closes.

g 1 A portion of the water from the conduit 81 is contact 92and movablecontact arm 93 which 'is moved .by the temperature responsive means 39.When the temperature responsive means is actuated by an abnormally hightemperature the contacts-92 and 93 abut so that the solenoid valvemechanism/91 allows water'to pass into the boiler as at 94, tonormalizeor lower. the temperature.

The contactarm 93 is preferably closed before the temperature responsivemeans moves the movablel arm. 31 to open the circuit. In the form shownthe, normalizing of the temperature by the injection of water can occurafter the supply of heat has been interrupted and as longv as thepressure responsive contacts and master switch remain closed, providedthe pump 5 1 is operating because of closure of contacts 71 and 72 aswell as 77 and '78.

In-Figure 2 I have shown a modification of my invention. A Water pump,101 is associated with the engine 17 and is' adapted to bedrivenvthereby. The pump draws water from the water. tank..4 I

52 through inlet che'c'kvalve 102 vand discharges it through outletcheck valve 103.. A solenoid mechanism 104 is included -in series withthe between the tank and .the pump contact 29 so that when the pressureresponsiye device 38 operates to open the circuit the check valve V102is held voff of its'seat and water surges discharged past valve 103.

4Water from the pump passes through a metering device 106 which includesorifices 107. and 108 in communication with the inlet` 84 of the boiler.Control of the orifice 107 is preferably by means'of a thumb screw- 109which can be adjusted to passav quantity of .water suflicient toaccommodate for the minimum heating rate or the minimum quantity` ofheatfwhich can be released to the boiler. To secure this, thetemperature responsive means 66 connected to' the rocker arm 69 is sodesigned that the valve-stem 111 actuated by the rocker arm is 'placed.in such a position, when the thermostat temperature is low, as' to.obstruct the orifice 108 so that the only lco water passed to theboiler vis through aperture 107..' However, 4-when the 'temperature ofthe` responsive means 66 rises, the'valve mechanism 11.1 is `caused toopen the passageway, through the orifice and allow additionalwater to.pass to the boiler.

A piston 112 is' also included in the metering,

.device andis biased by aspring 113 so that it `maintains a constantpressure drop across either one'or both of the orifices. This isaccomplished by providing thepump 101 with suchcapacity that an excessof water is always supplied to the metering device the piston 112bypassing any excess back to the tank 52" by means of a valve' 114 whichit operates and controls.

` .When the thermostat temperature is at a low value the orifice 108 isobstructed so that further water does not pass'therethrough. If the.pressure 'is low, the lsolenoid mechanism 104 is actuated to permitwater tobe passed to the boiler' under the control Aof .the pressureresponsive de vice 3 8 which can, when the pressure is up, ren-v der themechanism 104 effective to stop the pumping of open. v

waterbyholding check valve 102 The mod ication'shown inv Figure3-discloses an even simpler form-of the invention. In this form, the.4check valve mechanism -104- is con-` trolled by a circuit12lwhich-includes. a contact 1'22 carried by the rocker-arm69 and afixed contact 123. The circuit extends to the master switch-27 and, whenthe master switch' is Aclosed without beingv brought together so thatthe check'yalve 'mechanism l04'is operated to drop the inlet lcheckvalve 102 so that water -is supplied to the metering device from theengine operated pump'.` This' metering device includes an orifice -126controlledby valve mechanism 127'operablefrom the rocker arm 69. Aslidab'le piston 128 is included in the metering device and is biased byspring l129 -to maintain a constant pressure drop across the orifice'126 by diverting water to the tank 52 by `means of the valve 13,11whichit carries and controls. v

In the system of Figure 4, substantially the arrangement shown in Figurel is employed with the exception thatthe contact 77. is not connected'3A and the temperature of the thermostatic element `66 is sufficient,the contacts 122 and 123 are to contacts, such as '71 and 72, operatedby the means responsive to the fuel gas temperature for controlling thesupply of of said varying means.

r2. A boiler control'system comprising aforced circulation boiler, meansforreleasing heat to the boiler,4 and means for supplying water to .anintermediate part of the boiler in accordance with the temperature ofthe boiler steam and Water `independently 'means for supplying water tolthe foot of the ico t boiler in accordance with the temperatureqf'thefuel gases.

3. A b oiler control system comprising a forced circulation boiler,means for releasing heat to the boiler substantially in accordance withsteam withdrawn from theboiler', means for supplying .water vto theboiler, a first means for controlling waterl supplied to the boiler inaccordance with steam vtemperature therein, and a second means forindependently controlling additional water supplied to the boiler inaccordance 'with theA ,n

temperature of the fuel gases. 1

4. A fluid heater plant comprisinga forced cir-g culation heaterfor thefluid, means for passing a heating medium over the' heater to' heat thefluid therein, means for supplying main andan):- iliary feed' fluid `tothe heater at thermally spaced pointstherein, andme'ans responsive .'tothe temperature of the heating 'medium for controllingV v .the supply ofmain feed fluid only. f'

5. A boiler control system comprising a boiler tube, means for supplyingheat to said tubel by external` combustion; means for supplying liquidl, 1 'to the inlet of said tube means responsive to steamtemperature' insaid-tube for controlling the supply. of heat to said tube, andmeansresponsive .to the temperature of the products of said combustionforfindependently' controlling the supply of uqui'dmme' imerpf saidtube.

6.- Aboilei' control system comprising aforced.

`circulation boilerf tube, means'for heating 'said tube by externalcombustion, a first thermostat responsive to temperature ofthefproducts-of said combustion, a. second thermostat responsive totemperature .within said tube,- means for supplying 'water to the footof said tube under control of said first thermostat, means for supplyingaddtional water to said tube -immediately in 'adat a point between saidinlet and said outlet,

means for supplying water to the inlet of said tube under control ofsaid first thermostat, means for supplying additional water to said tubebetween said inlet and said point under control of said secondthermostat, and means responsive to la rise in temperature of saidsecond thermostat above a predetermined value for interrupting theoperation of said heating means.

8. A boiler control system comprising aV boiler tube having an inlet andan outlet, means for heating said tube by external combustion, means forsupplying water to the inlet `of said tube, means for supplyingadditional water to said tube at a point between said inlet and saidoutlet, a first thermostat responsive to the temperature of the productsof said combustion, means controlled by'said first thermostat upon avariation in the temperature thereof for varying the amount of saidwater admitted. to said inlet, a second thermostat responsive totemperature within said tube between said point and said outlet, meanscontrolled by said second thermostat upon an increase in the temperaturethereof above a predetermined value for admitting said additional waterto said tube at said point, and means controlled by said secondthermostat upon an increase in temperature thereof above a higherpredetermined valuefor interrupting the operation of said heating means.

9. A boiler control system comprising a boiler tube having an inlet andan outlet, means for heating said tube, means for supplying water' tothe inlet of said tube, means for supplying additional water to saidtube at a point between said inlet and said outlet, a thermostatresponsive to temperature within said tube between said point and saidoutlet, means controlled by said thermostat upon an increase in thetemperature thereof above a predetermined value for admitting saidadditional water to said tube at said point,.and means controlled bysaid thermostat upon an increase in temperature thereof above a higherpredetermined value for interrupting the operationof said heating means.

10. A boiler control system comprising a relatively long boiler tubehaving an inlet and an outlet, means for heating said tube, means forintroducing additional feed fluid into said tubebetween said inlet andsaid outlet, and tempera-` 'ture responsive means affected by saidadditional feed fluid for controlling said means for introducingadditional feed fluid and for interrupting the operation of said heatingmeans.

11. A boiler control system comprising a boiler tube having a main feedfluid inlet and an 'additional feed uid inlet, means for heating saidtube, means -for introducing feed fluid into said additional feed fluidinlet, and a thermostat responsive to tube temperature just beyond saidadditional feed fluid inlet for controlling said introducing means andfor interrupting the operation ofsaid heating means'.

12. A boiler control system comprising a boiler tube having a main feedfluid inlet and an additional feed fluid inlet, means for heating saidtube, means for introducing feed fiuid into said additional feed fluidinlet, means responsive to a predetermined .temperature of said tubejust beyond said additional feed fluid inlet for controlling saidintroducing means, and means responsive to a higher predeterminedtemperature of said tube for interrupting the operation of said heatingmeans. d

13. A boiler control system comprising a boiler tube having an auxiliaryfeed fluid inlet between its ends and a main inlet and outlet atopposite ends, means for supplying feed fluid to said aux-Y iliaryinlet, means for heating said tube, and means responsive to temperatureof said tube between said auxiliary inlet and said outlet forcontrolling said supplying means and interrupting the operation of saidheating means. l

14. A boiler control system comprising a boiler tube having an auxiliaryfeed fluid inlet between its ends and a main inlet and outlet atopposite ends, means for supplying feed fluid to said auxiliary inlet,means for heating said tube, means responsive to a predeterminedtemperature of said tube between said auxiliary inlet and said outletfor controlling said supplying means, and means responsive to a higherpredetermined temperature of said tubev between said auxiliary inlet andsaid outlet for controlling the operation of said lheating means.

15. A boiler control system comprising a boiler, a variable fuel burnerfor supplying variable quantities of heat to the boiler, means forsupplying water to the boiler, and means for controlling the watersupply means independently of variations in the operation of said burnerand in accordance with. the fuel gas temperature.

16. A boiler control system comprising a boiler of the forcedcirculation type, independently operable means for releasing heat invariable quantities to the boiler, independently operable means forsupplying water to the boiler, and means for controlling said watersupply means independently of variations in the operation of saidreleasing means and in accordance with the fuel gas temperature to'coordinate the water supply to the heat released to the boiler.

. ABNER DOBLE.

